POS1413 INTERSTITIAL LUNG DISEASE(ILD) PREVALENCE AND TRENDS IN SYSTEMIC LUPUS ERYTHEMATOSUS(SLE), RHEUMATOID ARTHRITIS(RA), SCLERODERMA(SCL), MYOSITIS AND MIXED CONNECTIVE TISSUE DISEASES(MCTD) ALONG WITH COMPARISON OF LENGTH OF HOSPITALIZATION STAY(LOS), COST AND RACIAL PREDISPOSITION AMONG THESE PATIENTS
Authors: A. Hussain, P. Khandwala, D. Desai
Journal: Annals of the Rheumatic Diseases (2022)

Background ILD includes a category of lung disorders seen in a variety of autoimmune conditions. Prevalence of ILD in autoimmune diseases is variable and poorly studied. ILD is more commonly seen in systemic sclerosis, with 90% of patients showing some interstitial changes on High resolution CT scan. ILD is less common in SLE compared to SCL, with ILD not only a complication but also a poor prognostic factor in these patients. Prior studies have shown increased prevalence of ILD in RA patients over the years. For myositis, ILD can develop during the course of disease or can precede the diagnosis in a small subset of patients. Objectives Our study aims to determine the prevalence of ILD in diseases like SLE, Scleroderma, RA, MCTD, and Myositis over the years as well as identify racial predisposition, LOS, Cost of hospitalization in these patients Methods We used the Nationwide Inpatient Sample database (years 2003-2018) and extracted patients with ILD using validated International Classification of Disease (ICD) codes. Data from 2015 was excluded from the study in light of the transition of the coding system from version 9 to 10. We identified cases having the diagnosis of SLE, RA, Scleroderma, MCTD or Myositis. Prevalence as well as demographics, cost of hospitalization, and length of stay (LOS) was analyzed and charted. Data was analyzed using statistical analysis system 9.4 software. Results We identified a total of 149,691 cases of ILD over 15 years. Patients with RA had the highest prevalence of ILD amongst the 5 studied autoimmune diseases. The prevalence rate of RA in ILD patients in 2003 was 3.3% which significantly reduced to 0.93% in 2018, with a peak of 6.42% seen in 2010 (p &lt;0.0001). Prevalence rate of ILD with myositis decreased from 0.72% in 2003 to 0.46% in 2018 (p 0.0001). The prevalence rates of SLE, Scleroderma, and MCTD in cases with ILD significantly increased from 1.38% to 1.63%, 1.38% to 1.76%, and 0.14% to 0.54% from 2003 to 2018 respectively. The average age of ILD cases with SLE was significantly younger compared to ILD without autoimmune disease (59.28 vs 72.32 years, p &lt;0.0001), RA (69.72 vs 72.17 years, p &lt;0.0001), Scleroderma (62.01 vs 72.28 years, p &lt; 0.0001), Myositis (59.56 vs 72.19 years, p &lt;0.0001) and MCTD (59.6 vs 72.18 years, p &lt;0.0001). On examining the racial distribution, the African American population with ILD when compared to other races were more likely to have underlying SLE, MCTD, Myositis or Scleroderma. In ILD with RA, Native Americans were the most affected racial demographic followed by African Americans. Average cost of hospitalization was higher in ILD with MCTD ($104,631 vs $71,264.6, p&lt;0.0001), Myositis ($105,623 vs $71,232.9, p&lt;0.0001) and Scleroderma ($88,736.2 vs $71,135.5, p&lt;0.0001). Average LOS was significantly longer in RA (7.17 vs 6.66 days, p value 0.0006), MCTD (7.71 vs 6.67 days, p value 0.0008), Myositis (8.33 vs 6.66 days, p value &lt;0.0001) and Scleroderma (7.07 vs 6.67 days, p value 0.0176). Though not significant, average LOS was longer in SLE (6.79 vs 6.67 days, p value 0.4999). Conclusion Our study shows that the prevalence of RA in ILD cases has significantly reduced through the years. This can be attributed to the better understanding of the disease and its risk factors as well as the availability and use of newer biologic agents to obtain better control. However, the prevalence of SLE, Scleroderma, and MCTD in ILD cases has increased over the years. This points to the need for better therapies as well as highlights the fact that the overall recognition and diagnosis of these diseases have increased over the years. Racial predilection also comes to light, suggesting the need for special attention to certain races to diagnose the autoimmune disease earlier. Average LOS and cost of hospitalization were also higher in ILD cases with autoimmune disease, reflecting the higher socioeconomic burden. Disclosure of Interests None declared